feat(query): expose scanned bytes/rows and surface query_run_id

[zfarrell]

Expose bytes_scanned/rows_scanned from the query-run history API in hotdata queries, and surface query_run_id in hotdata query output (footer + JSON) so the run lookup is actually reachable. The query JSON body now serializes the response struct directly.

BREAKING CHANGE: hotdata query --output json no longer emits preview_row_count (use row_count), and the warning field is now stderr-only rather than in the JSON body.

[claude]

nit: (not blocking) Serializing the struct directly drops the preview_row_count field the old result_json emitted, so this is a backward-incompatible change to the --output json shape. The value is still recoverable from row_count (they were always equal), but any consumer reading preview_row_count will now get undefined. Worth confirming this is intended and noting it in the changelog / release notes if the JSON output is a public contract.

[claude]

Approving. One non-blocking note left inline about the removed preview_row_count field in the --output json shape. Otherwise the changes are consistent with existing patterns (double-option flatten + clamp, warning stays stderr-only) and well covered by tests.

[codecov]

Codecov Report

❌ Patch coverage is 82.14286% with 20 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/commands/query.rs	84.90%	8 Missing ⚠️
src/commands/queries.rs	83.33%	6 Missing ⚠️
src/commands/usage.rs	0.00%	6 Missing ⚠️

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